To all whom it may concern



S. L. DONNELL.

LeveL No. 60346. A mentari Dec. 11, I1866.

N. PETERS. PHOTOUTMOGRAPHER. WASHINGTN. D C.

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TO ALL WHOM IT MAY CONCERN: d

Beit known that I, SAMUEL L. DONNELL, of Spring Creek, Madison county, `State of Tennessee; have invented new and useful improvements in Levellingor Grading Instruments; and I dolhereby declare that the following is a full, clear, and exact description thereof, which will enable others skilled in theart tomake and use the same, reference being had to the accompanying drawing, forming part of this, specification. d

The present invention relates to certain new and useful improvements in `a levelling or grading instrument, invented and secured to me by Letters PatentY of the United States, bearing date the eleventh day of September, A. D. 1860, and numbered 29,955; and it consists in a novel arrangement and construction of the levelling or grading instrument, whereby simplicity and eihciency are secured, and theinstrument also susceptibleof a much easier and a more ready adjustment oi'its several parts, according as may be desired or necessary, as

will be plainlyapparent from the following detail description thereof, reference being had to `the accompanying plate of drawings, in which- Figure lis a side elevation of the instrument, with some portions in central vertical section. t l

Figure 2 an elevation oi' the front side or end of the instrument, with its stand or support broken oif.

Figures 3, 4, Iand 5,`detail views, to be hereinafter referred to. 7

Similar letters of reference indicate like parts.

A, in the drawings, represents the stand or support of the instrument, `the foot, Bof which, may be made removable ordetachable for transportation. `'Ihe stand is hollow, and the squareV rod, e, which supports the bubble block, D, is inserted in the hollow stand, vand can be raised or lowered in height or position, and there 4supported by means of a spring lever catch or pawl, E, hung in the slot, F, of the stand A. i Around and upon the upper end of the square rod c, a collar er ring, Gr, Yis swivelled, having hung to its upper side the bubble` block D, hereinbefore referred to, by means of the trunnion pins, a, projecting from cachot' lits sides, and at points midway between its two ends. Hg a balance weight or ball, having a holethrough its centre, which ball is placed over thesta' of the stand A, and is suspended by means of connecting link-pieces or chains, ,I, one upon each side, and at' points diametrically` opposite to each other, to staples or lugs, 3 upon the under side of the bubble block. One of these staples J, or that at the end of Athe bubble block, at which the eye is placed for v sighting, is arranged within a slot K, extending in the direction of the length of the bubble block, and has vscrewed into it, upoirthe insideV of the blocl't, a thumlscrew, L, the milled head, M, of which is at the sight end i of the block G. The other staple, J2, is fixed in the under side of the bubble block, at a short distance from the opposite end to that at which the eye is placed for sighting.` In the 4under side of the bubble block D is a fixed post or standard, N, through whichpasses a set orithuinb screw, o, having amilled head, P, upon` its` outer` end, and by its inner end bearing against the side of the collar Gr, swivelled on thestand From the above description of the arrangement of the bubble block upon the stand A, it is plain to be seen that, first, by turning the thumb-screw at the sighting end of the bubble block, either `to the right or left, the

lug into which it is screwed and to which v the balance weight or ball H is hung, will consequently be moved v either toward or away from the centre stai? or stand A, as the case may be, and thusithrough the link-piece` connecting such lug with the balancing weight, bringing said weight to the proper adjustment for the balancing and the adjustment of the bubble block, the hole through the said weight or` ball H being made large, so as to allow a freedom of movement to the ball, and also to its above-described adjustment; that, secondly, the bubble block is susceptible of being swung round upon its stand, so as to be sighted in any direction, and thatfthirdly, after the bubble block has been adjusted in position, as described above, it can be there held and secured, as it were, by simply bringing the thumb or set screw o against the collar G of the stand A. In order to enablethe bubble block to be adjusted with more nicety, I have inserted at its opposite end to that at which the sighting is done, a thumb-screw, D, that, by beinglsimply screwed 1into or out of the blo,ck,1aii`e`cts or `changeaits balance, as is obvious without any further explanation. To adjust the sights at each end ofthe bubble block, a s`et-`screw or thumb-screw, R, for each sight, is provided, that, by being screwed into or outof the arms, S, by which the sights are secured to the said block D, raise or lower the sights `from the block, as is evident from an inspection of tig.` l of the drawings, each sight being slotted vertically at T, and each similarlymgradliated about such slots and moving over fixed pointers, U, of the block, so that they can bothbe brought or adjusted to uniform height.

It may be here remarked in conclusion, that a telescope and compass can be mounted upon the bubble clock, if sodesired, to be used in lieu of the open sights, in which case it would be desirableA to employ a. swivel, V, turning, upon transverse centres o1` pivotsso as to enable the compass to be always level as :the balance ball is adjusted, which form of swivel is shown in figs. 4 and` 5 of the drawings.

I claim as new, and desire to secure by Letters Patentl. The bubble block D, mounted upon a collar Gr, swivelled upon the stand Aoi its'equivalent, 'in combination withY the balance ball or weight H, suspended from the said block and about-and around the stand A, substantially as herein described and for the purpose spcciiied.

2. ln eombination with the above, arranging either one o): both of tbe lugs J J2, in the bubble block D, from which the balance. ball H is suspended in such a manner as to be susceptible of being adjusted therein, substzmtially as and for the purpose described.

3. The combination with Elie sights of the bubble block of the thumb or set screws R, and xedipintcr U, arranged 'substantially as described and for the purpose set fortli.

L The use of a. transverse swivelled block V, forV the purpose described.

.SAMUEL L. DONNELL. Witnesses c E. A. CLARK, G. A. MAXEY. 

